Scapy - Scapy is a powerful interactive packet manipulation program.
Ping Meter Gadget - Customizable, graphical, semi-transparent ping (latency) meter.
Winsock Packet Editor - WPE Pro is a packet editor.
Fping (open source) - fping is a program to send ICMP echo probes to network hosts, similar to ping, but much better performing when pinging multiple hosts.
Nipper - Nipper - Neat Internet Protocol Packet EditoR - is a graphical packet generation tool.
PingDoctor - PingDoctor is software that is considered to be the most powerful and easiest to use network route analyzer.